fix(pptEasyClass): 修复特定场景下回退按钮和弹窗显示逻辑异常

调整了返回按钮显示条件以及弹窗触发条件，补充了noLogin !=3的判断逻辑，修正了之前的判断疏漏

src/components/pptEasyClass/index.vue

@@ -7,7 +7,7 @@
       <div class="pec_header">
         <div class="pec_h_left">
           <!-- || tType == 1 -->
-          <div @click.stop="back" class="backBtn" v-if="screenType != 2 && noLogin != 2">
+          <div @click.stop="back" class="backBtn" v-if="screenType != 2 && noLogin != 2 ">
             <img src="../../assets/icon/newIcon/return.svg" alt="" />
           </div>
           <div @click.stop="gotoCourseManage" class="backBtn" v-if="screenType == 2 && tType == 1 && noLogin != 2">
@@ -673,7 +673,7 @@ export default {
           }
           this.setPptIframe()
           this.classList = res.data[2]
-          if(!this.tcid2 && this.tType == '1' && this.noLogin != 2){
+          if(!this.tcid2 && this.tType == '1' && this.noLogin != 2 && this.noLogin != 3){
             this.$refs.selectTeachingClassDialogRef.open({classList:this.classList})
           }
           this.pageLoading = false;